Devices for compression and corresponding expansion of data are known in the art.
It is known in a data transfer terminal to compress the transmittal data by providing a fixed library of commonly used phrases at the receiver, and upon the occurrence of one of the phrases, transmitting only the address of that phrase. Such a device is shown in U.S. Pat. No. 4,107,457 issued Aug. 15, 1978 for an invention of Thomas M. Hajduk.
It is also known to check directly, consecutive repetitions of a character and transmit only the character code and repetition count, as shown in the device of U.S. Pat. No. 4,192,966 issued Mar. 11, 1980 for an invention of Mark Mayer.